1. Field of the Invention
The present invention relates to an image forming apparatus and image forming method which can form images on both sides of a sheet of recording paper.
2. Description of the Related Art
Copying machines as image forming apparatuses which can print images on both sides of a sheet of recording paper P include a copying machine as shown in FIG. 1 which operates in a mode of reading an image from a document D having an image drawn on one side and printing the image on both sides of the sheet of recording paper P (hereinbelow, referred to as xe2x80x9cS-D modexe2x80x9d) and a copying machine as shown in FIG. 9 which operates in a mode of reading images from a document D having images drawn on both sides and printing the images on both sides of the sheet of recording paper P (hereinbelow, referred to as xe2x80x9cD-D modexe2x80x9d). Each of such copying machines comprises, broadly, an image reading part for reading an image of the document D, a document transport part for transporting the document D to the image reading part, an image forming part for printing the read image onto the sheet of recording paper P, and a recording paper transport part for transporting the sheet of recording paper P to the image forming part.
FIG. 15 is a block diagram of a copying machine of a related art which operates in the S-D mode. The copying machine comprises a control unit 101, an operation panel 102, a reading side drive source 103, a body side drive source 104, a printing control unit 105, and a sheet reversal control unit 106. The components are connected via a bus line 107. The control unit 101 realized by a CPU (central processing unit) or the like controls the operation of the whole copying machine. The reading side drive source 103 is driven in response to designation of start of copying from the operation panel 102, the document D is transported to the image reading part, and an image is read. The body side drive source 104 is also driven, thereby transporting the sheet of recording paper P to the image forming part. The printing control unit 105 prints the read image onto the sheet of recording paper P by controlling the image forming part. The sheet reversal control unit 106 turns the sheet of recording paper P upside down so that the images are printed on both sides of the sheet of recording paper P by controlling the recording paper transport part.
FIG. 16 is a flowchart showing an image forming operation of the copying machine of FIG. 15. When an image of the document D is read in step S1, the image is printed on one of the surfaces of the sheet of recording paper P in step S2. The routine progresses to step S3 where an image on the next document D is read. Further, the routine advances to step S4 where the sheet of recording paper P having the image printed on one of the surfaces is turned upside down. In step S5, the image read in step S3 is printed on the other surface of the sheet of recording paper P. In step S6, whether there is the next document D or not is determined. When there is the next document D, the routine is returned to step S1. When there is no document D, the operation is finished.
FIG. 17 is a block diagram of a copying machine of another related art which operates in the D-D mode. The block diagram of the copying machine is obtained by eliminating the printing control unit 105 in FIG. 15 and adding an odd-numbered page printing control unit 108, an even-numbered page printing control unit 109, and a document reversal control unit 110 to FIG. 15. The same blocks are designated by the same reference numerals and their description is omitted here. The odd-numbered page printing control unit 108 controls an operation of printing the read image onto one of the surfaces of the sheet of recording paper P. The even-numbered page printing control unit 109 controls the operation of printing the read image onto the other surface of the sheet of recording paper P. The document reversal control unit 110 turns the document D upside down in order to read images on both sides of the document D.
FIG. 18 is a flowchart showing an image forming operation of the copying machine of FIG. 17. In step S11, an image on the surface of the document D is read. In step S12, the image is printed on one of the surfaces of the sheet of recording paper P. The routine advances to step S13 where the document D is turned upside down. Further, in step S14, the sheet of recording paper P is turned upside down. In step S15, an image on the back of the document D is read. In step S16, the image is printed on the other surface of the sheet of recording paper P. In step S17, whether there is the next document D or not is determined. If there is the next document D, the routine is returned to step S11. When there is no next document D, the operation is finished.
Japanese Unexamined Patent Application JP-A 63-224468 (1988) discloses a copying machine having a memory for storing read image information. Further Japanese Unexamined Patent Application JP-A 5-183706 discloses a copying machine such constituted that images of all documents are read only on time and stored in a memory to thereafter form a necessary volume of copies by reading the image data from the memory.
When continuous copying operations are performed by the copying machines of the related arts which operate in the S-D and D-D modes, such an inconvenience occurs that the printed faces of the sheets of recording paper P which are printed and ejected are not arranged in order of page. Referring to FIG. 8A, a specific description regarding first to third ejected sheets of recording paper P1 to P3 will be given as an example. The second sheet of recording paper P2 is stacked on the first sheet of recording paper P1 and the third sheet of recording paper P3 is stacked on the second sheet of recording paper P2. In each of the sheets of recording paper P1 to P3, the odd-numbered page is arranged to be on the surface (the top face in FIG. 8A) side of the sheet of recording paper and the even-numbered page is arranged to be on the back (the under face in FIG. 8A) side of the sheet of recording paper. The order of pages becomes, therefore, 2, 1, 4, 3, 6, and 5.
In the copying machines of Japanese Unexamined Patent Publications JP-A 63-224468 (1988) and JP-A 5-183706 (1993), since the storage capacity of the memory is limited, an inconvenience such that a large amount of image information to be read cannot be stored occurs. Since the storage capacity is fixed, the memory cannot be efficiently used. Additionally the copying machine disclosed in JP-A 5-183706 (1993) it is necessary to select a sequence of reading image data from the memory, in order to arrange the printed faces of the ejected sheets of recording paper in order of page. A mechanism for reversing faces of the ejected sheet of recording paper is required.
It is an object of the invention to provide an image forming apparatus and image forming method which can eject sheets of recording paper after image formation in the S-D and D-D modes in accordance with the order of pages.
The invention relates to an image forming apparatus comprising:
reading means for reading an image on a document;
document transporting means for sequentially transporting documents to the reading means;
image forming means for forming an image on a sheet of recording paper;
recording paper transporting means for transporting the sheet of recording paper; and
storing means for storing image information read by the reading means,
the apparatus comprising control means for allowing an image drawn on one side of each document to be sequentially read by the reading means and formed on both sides of each sheet of recording paper by the image forming means,
the control means allowing an image of an odd-numbered document to be read by the reading means and stored into the storing means,
allowing an image of an even-numbered document to be read by the reading means and formed on one of the surfaces of a sheet of recording paper by the image forming means,
allowing the sheet of recording paper to be turned upside down by the recording paper transporting means,
allowing the image stored in the storing means to be read out and formed on the other surface of the sheet of recording paper by the image forming means, and
allowing the sheet of recording paper to be transported with the other surface facing downward by the recording paper transporting means.
According to the invention, an image of an odd-numbered document is read and stored. Subsequently, an image of an even-numbered document is read and formed on one of the surfaces of a sheet of recording paper. Further, the sheet of recording paper is turned upside down, and the stored image is read out and formed on the other surface of the sheet of recording paper. Finally, the sheet of recording paper is transported with the other surface facing downward. Consequently, at the time of execution in the S-D mode, the order of pages of the sheets of recording paper after image formation becomes 1, 2, 3, 4, . . . . Thus, the sheets of recording paper can be ejected in accordance with the order of pages.
According to the invention as mentioned above, an image of an odd-numbered document is read and stored. Subsequently, an image of an even-numbered document is read and formed on one of the surfaces of a sheet of recording paper. Further, the sheet of recording paper is turned upside down, and the stored image is read out and formed on the other surface of the sheet of recording paper. Finally, the sheet of recording paper is transported with the other surface facing downward. Consequently, at the time of execution in the S-D mode, the sheets of recording paper can be ejected in accordance with the order of pages.
In the invention it is preferable that the apparatus further comprises:
detecting means for detecting the size of the document;
determining means for comparing the size of the detected document with a size of a predetermined reference document and determining whether the detected document is larger or not; and
thinning means for thinning out image information read from the document when the detected document is larger on the basis of the determination result and storing the resultant image into the storing means.
According to the invention, at the time of execution in the S-D mode, when it is determined that the document is larger than the predetermined reference document, that is, when it is determined that all of the read image information cannot be stored into the storing means, the read image information is thinned out and stored. The sheets of recording paper can be, therefore, certainly arranged in order of page irrespective of the size of a document, namely, an amount of image information to be read.
According to the invention, at the time of execution in the S-D mode, when the document is larger than the predetermined reference document, the read image information is thinned out and stored. Thus, the sheets of recording paper can be certainly arranged in order of page irrespective of the size of the document.
In the invention it is preferable that the storage capacity of the storing means is determined on the basis of an amount of image information read from the first document.
According to the invention, at the time of execution in the S-D mode, the storage capacity of the storing means for storing the image information is determined on the basis of the amount of the image information of the first document. Consequently, the subsequent image information can be certainly stored and the storing means can be efficiently used.
The storage capacity determined based on the image information amount of the first document is set to the predetermined reference document. For example, when an image information amount of the second document is detected and the image information amount is larger than that of the first document, the image information of the second document can be thinned out. Consequently, the operation of setting a specific value as the size of the reference document is made unnecessary and the construction can be simplified. Since the setting operation of the operator becomes unnecessary, the convenience can be improved.
According to the invention, at the time of execution in the S-D mode, since the storage capacity of the storing means is determined on the basis of the image information amount of the first document, the subsequent image information can be certainly stored and the storing means can be efficiently used. By setting the storage capacity determined on the basis of the image information amount of the first document as the size of the reference document, the operation of setting a specific value as the size of the reference document is made unnecessary and the construction can be simplified. Since the setting operation of the operator becomes unnecessary, the convenience can be improved.
The invention relates to an image forming apparatus comprising:
reading means for reading an image on a document;
document transporting means for sequentially transporting documents to the reading means;
image forming means for forming an image on a sheet of recording paper;
recording paper transporting means for transporting the sheet of recording paper; and
storing means for storing image information read by the reading means,
the apparatus comprising control means for allowing images drawn on both sides of each document to be sequentially read by the reading means and formed on both sides of each sheet of recording paper by the image forming means,
the control means allowing an image on the surface of a document to be read by the reading means and stored into the storing means,
allowing an image on the back of the document to be read by the reading means and formed on one of the surfaces of a sheet of recording paper by the image forming means,
allowing the sheet of recording paper to be turned upside down by the recording paper transporting means,
allowing the image stored in the storing means to be read out and formed on the other surface of the sheet of recording paper by the image forming means, and
allowing the sheet of recording paper to be transported with the other surface facing downward by the recording paper transporting means.
According to the invention, an image on the surface of a document is read and stored. Subsequently, an image on the back of the document is read and formed on one of the surfaces of a sheet of recording paper. Further, the sheet of recording paper is turned upside down, and the stored image is read out and formed on the other surface of the sheet of recording paper. Finally, the sheet of recording paper is transported with the other surface facing downward. Accordingly, at the time of execution in the D-D mode, the order of pages of the sheets of recording paper after image formation becomes 1, 2, 3, 4, . . . . Thus, the sheets of recording paper can be ejected in accordance with the order of pages.
According to the invention, an image on one of the surfaces of a document is read and stored, an image on the other surface of the document is read and formed on one of the surfaces of a sheet of recording paper, the sheet of recording paper is turned upside down, the stored image is read out and formed on the other surface of the sheet of recording paper, and finally, the sheet of recording paper is transported with the other surface facing downward. Thus, the sheets of recording paper can be ejected accurately in accordance with the order of pages at the time of execution in the D-D mode.
In the invention it is preferable that the apparatus further comprises:
detecting means for detecting the size of the document;
determining means for comparing the size of the detected document with the size of a predetermined reference document and determining whether the detected document is larger or not; and
thinning means for thinning out the read image information when the detected document is larger on the basis of the determination result and storing the resultant information into the storing means.
According to the invention, at the time of execution in the D-D mode, when it is determined that the document is larger than the predetermined reference document, that is, when it is determined that all of the read image information cannot be stored into the storing means, the read image information is thinned out and stored. Consequently, the sheets of recording paper can be certainly arranged in accordance with the order of pages irrespective of the size of the document, namely, the amount of image information to be read.
According to the invention, at the time of execution in the D-D mode, when the document is larger than the predetermined reference document, the read image information is thinned out and stored. Thus, the sheets of recording paper can be certainly arranged in accordance with the order of pages irrespective of the size of the document.
In the invention it is preferable that the storage capacity of the storing means is determined on the basis of the amount of the image information read from the surface of the first document.
According to the invention, at the time of execution in the D-D mode, the storage capacity of the storing means for storing image information is determined on the basis of the amount of image information on the surface of the first document. Consequently, the subsequent image information can be certainly stored and the storing means can be efficiently used.
The storage capacity determined on the basis of the amount of the image information on the surface of the first document may be set as the size of the predetermined reference document. Consequently, the operation of setting a specific value as the size of the reference document is made unnecessary and the construction is simplified. The setting operation of the operator is also made unnecessary, thereby enabling the convenience to be improved.
According to the invention, at the time of execution in the D-D mode, the storage capacity of the storing means is determined on the basis of the amount of the image information on the surface of the first document, so that the subsequent image information can be certainly stored and the storing means can be efficiently used. By setting the storage capacity determined on the basis of the amount of the image information on the surface of the first document as the size of the reference document, the operation of setting a specific value as the size of the reference document is made unnecessary and the construction can be simplified. The setting operation of the operator is also made unnecessary, thereby enabling the convenience to be improved.
The invention relates to an image forming method of sequentially reading images drawn on one sides of documents and forming the images on both sides of a sheet of recording paper, comprising:
a step of reading and storing an image of an odd-numbered document;
a step of reading an image of an even-numbered document and forming the image on one of the surfaces of a sheet of recording paper;
a step of turning the sheet of recording paper upside down;
a step of reading out the stored image and forming the image on the other surface of the sheet of recording paper; and
a step of transporting the sheet of recording paper with the other surface facing downward.
According to the invention, by the image forming method, the sheets of recording paper can be arranged in accordance with the order of pages at the time of image formation in the SD mode.
According to the invention, the image forming method by which the effect is obtained in the S-D mode can be provided.
The invention relates to an image forming method of sequentially reading images drawn on both sides of a document and forming the images on both sides of a sheet of recording paper, comprising:
a step of reading and storing an image on the surface of a document;
a step of reading an image on the back of the document and forming the image on one of the surfaces of the sheet of recording paper;
a step of turning the sheet of recording paper upside down;
a step of reading out the stored image and forming the image on the other surface of the sheet of recording paper; and
a step of transporting the sheet of recording paper with the other surface facing downward.
According to the invention, by the image forming method, sheets of recording paper can be arranged in accordance with the order of pages at the time of the image formation in the D-D mode.
According to the invention, the image forming method by which the effect is obtained in the D-D mode can be provided. Additionally, according to the invention, by providing only one memory for one page it is achieved without any consideration of image data readout sequence to form images on both sides of sheets of recording paper in the S-D mode and D-D mode and eject the sheets of recording paper in order of page. No mechanism for reversing the ejected sheets of recording paper is required, which results in reduction in manufacturing costs. A vicinity of a sheet ejection unit can be constituted compact, whereby the apparatus can be reduced in size as a whole.